Mikaela Mayer is no longer fighting in the co-feature of Tuesday night's Top Rank boxing card in Las Vegas after testing positive for the coronavirus.
Mayer, 29, announced the results of her test on Instagram on Sunday. She was scheduled to be the co-featured bout against Helen Joseph.
"It came as a complete surprise," Mayer wrote. "I am currently asymptomatic and am quarantining at an off-site location per recommended guidelines. The rest of my team tested negative and they are all in good health.
"I was really looking forward to bringing back boxing for all of you and I'm disappointed for myself, my team, my supporters and for my opponent, Helen Joseph, who worked just as hard to be here this week and put on a show for everyone."
Mayer said later in the post that there was a chance the test result could be a false positive, but Top Rank's protocols for Tuesday's fight do not allow for retesting. If a positive test comes up at any point during the prefight process, the fighter is immediately taken off of the card and quarantined outside of the MGM bubble.
"The bottom line is if someone comes up positive on their test, there's no retest," Top Rank COO Brad Jacobs told ESPN last month. "There's no 'Oh man, the thing was wrong.' You're done. Very simple."
The reason for this policy was to keep any potentially infected fighters out of the MGM bubble before they could enter and possibly cause a spread. Evan Korn, a spokesman for Top Rank, said there have been no other positive tests for fighters or teams for Tuesday's card, which is headlined by Shakur Stevenson.
The undefeated Mayer (12-0) had spent the majority of the past two months in Washington, D.C., and Houston in training camp after driving with her two dogs and best friend, Ginny Fuchs, from her Colorado home.
While in Houston, the gym where Mayer was training, Main Street Boxing, had reopened to the public. Before she learned the tests results, Mayer had told ESPN she was concerned once the gym opened -- not necessarily for herself but for her coaches, Kay Koroma and Al Mitchell.
"Super weird and a little nerve-wracking because all of a sudden the gym is packed with younger people, and I'm like, 'How safe are these young people being before they come into this gym,'" Mayer said last month. "Even though I wasn't quarantined at home like a lot of people were, locked in their house, I was on the road doing things, I was very cautious."
Mayer told ESPN she continually washed her hands after touching public surfaces, used antibacterials and didn't touch her face. Other than her time in the gym, she also limited those around her to Fuchs and her coaches. She told ESPN the only time she was around the gym with other people during camp was during sparring sessions.
She considered training solo but needed the sparring work during her camp -- a camp she felt good about coming off a training camp to initially fight Melissa Hernandez on March 17. That fight, scheduled for New York, was postponed because of the pandemic. This is the second straight fight that has been called off for Mayer because of the impact of COVID-19.
Mayer is driving back to Colorado Springs by herself, while Mitchell is flying back to Marquette, Michigan. Koroma is staying in Las Vegas to work with Stevenson.
Mayer's manager, George Ruiz, told ESPN they've already had discussions with Top Rank to try to get Mayer back in the ring later this summer, as long as she eventually tests negative for COVID-19.
Mayer had been looking forward to being on the first card back on ESPN because of both boxing getting back and the potential extra exposure it could bring.
"That was one of the things I thought about and I thought about it after the UFC had their first card a couple of weeks ago, right," Mayer told ESPN last month. "ESPN and ESPN+ views were through the roof and I'm like, 'Wow, if we do get this fight to go through in early June, there's going to be a lot of people watching.'
"Even people who don't usually watch boxing, they just need some sports in their life because there's no sports happening right now other than old replays. They are going to tune into these fights so I want to put on a good performance."
Now, with a positive test derailing her fight, Mayer said she "will just have to take a quick break, but I will be in the ring soon."
ESPN's Steve Kim contributed to this report.